1. Field of the Invention
The present invention relates generally to a servo information writing method of writing servo information of a disk drive to a disk medium, and more particularly, it relates to a method of writing servo information including positioning correction information.
2. Description of the Related Art
In recent years, in a disk drive represented by a hard disk drive, servo information (servo pattern) for use in head positioning control is recorded on a disk medium for use as a data recording medium.
In steps of manufacturing the disk drive, a servo writing step of recording the servo information on the disk medium is one of the important steps which influence efficiency of the whole manufacturing steps. Therefore, there have been proposed or developed various types of servo writing methods in order to enhance the efficiency. In the methods, there has been noted a magnetic transfer method in which the servo information is transferred and recorded from a disk as a master board to the disk medium incorporated in the disk drive by a magnetic transfer process.
Additionally, the servo information (hereinafter referred to as the original servo information) of a transferor recorded in the master board has a possibility that distortion is generated by, for example, an attaching error in attaching the master board to a device for writing the original servo information.
Moreover, in the steps of manufacturing the disk drive, disk eccentricity is sometimes generated in the disk medium by an assembly error or the like in a step of assembling the disk medium into the drive. Therefore, there is a high possibility that a positioning error is caused by the distortion of the original servo information and the disk eccentricity of the disk medium, when the head positioning control is executed in the disk drive by use of the original servo information transferred to the disk medium as such.
To solve the problem, there is proposed a method of measuring the disk eccentricity for each disk medium in which the servo information is recorded to record the disk eccentricity as positioning correction information on the disk medium (see, e.g., Jpn. Pat. No. 3295940).
A conventional method is a method of measuring the disk eccentricity (as a result, the distortion of the servo information) for each disk medium to produce the positioning correction information, and recording the information on the disk medium. However, in this method, time required for the servo writing step increases as much as time required for processing to produce the positioning correction information for each disk medium.